U.S. patent application number 14/110885 was filed with the patent office on 2014-01-23 for wiper control apparatus.
This patent application is currently assigned to Hitachi Automotive Systems, Ltd.. The applicant listed for this patent is Yoshiyuki Sasada. Invention is credited to Yoshiyuki Sasada.
Application Number | 20140023239 14/110885 |
Document ID | / |
Family ID | 47009197 |
Filed Date | 2014-01-23 |
United States Patent
Application |
20140023239 |
Kind Code |
A1 |
Sasada; Yoshiyuki |
January 23, 2014 |
WIPER CONTROL APPARATUS
Abstract
A wiper control apparatus is provided which detects a visibility
state of a window of a moving body and controls a wiper to a target
visibility state with less erroneous operation and in a short time.
The wiper control apparatus provided in a vehicle and for
controlling the wiper operating on the window of the vehicle
includes a wiper position detection unit to detect a position of
the wiper on the window of the vehicle, a recognition rate
calculation unit to calculate a recognition rate of an image taken
by an imaging device when the position of the wiper detected by the
wiper position detection unit is a previously determined position,
a target recognition rate setting unit to set a target recognition
rate from the calculated recognition rate, a comparison unit to
compare the recognition rate with the target recognition rate and
to output a comparison result, and a wiper operation speed
determination unit to determine an operation speed of the wiper
based on the comparison result.
Inventors: |
Sasada; Yoshiyuki;
(Hitachinaka-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sasada; Yoshiyuki |
Hitachinaka-shi |
|
JP |
|
|
Assignee: |
Hitachi Automotive Systems,
Ltd.
|
Family ID: |
47009197 |
Appl. No.: |
14/110885 |
Filed: |
April 2, 2012 |
PCT Filed: |
April 2, 2012 |
PCT NO: |
PCT/JP2012/058801 |
371 Date: |
October 9, 2013 |
Current U.S.
Class: |
382/104 |
Current CPC
Class: |
B60S 1/0844 20130101;
B60S 1/08 20130101; G06K 9/00791 20130101 |
Class at
Publication: |
382/104 |
International
Class: |
B60S 1/08 20060101
B60S001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 11, 2011 |
JP |
2011-086903 |
Claims
1. A wiper control apparatus provided in a vehicle and for
controlling a wiper operating on a window of the vehicle,
comprising: a wiper position detection unit to detect a position of
the wiper on the vehicle window; a recognition rate calculation
unit to calculate a recognition rate of an image taken by an
imaging device when the position of the wiper detected by the wiper
position detection unit is a previously determined position; a
target recognition rate setting unit to set a target recognition
rate from the calculated recognition rate; a comparison unit to
compare the recognition rate with the target recognition rate and
to output a comparison result; and a wiper operation speed
determination unit to determine an operation speed of the wiper
based on the comparison result.
2. The wiper control apparatus according to claim 1, wherein the
recognition rate is set from a change amount in light amount
between a previously determined noted pixel and an adjacent pixel
adjacent to the noted pixel in the taken image.
3. The wiper control apparatus according to claim 1, wherein the
recognition rate is set from a change amount between a light amount
of a taken image of a just previous frame and a light amount of a
taken image of a current frame.
4. The wiper control apparatus according to claim 1, wherein the
previously determined position is a position just after the wiper
exceeds an imaging range of the imaging device.
5. The wiper control apparatus according to claim 1, wherein an
inner parameter of one imaging device and an inner parameter of the
other imaging device are derived, and the recognition rate is set
from a change amount of the derived inner parameters.
Description
TECHNICAL FIELD
[0001] The present invention relates to a wiper control apparatus
for controlling a wiper operating on a window of a moving body such
as an automobile.
BACKGROUND ART
[0002] As a technique to automatically operate a wiper, there is
Patent Literature 1. Patent Literature 1 discloses a visibility
state detection apparatus for detecting a visibility state through
a windshield of a moving body, which includes a camera to take in
an image of a comparable object outside the moving body through the
windshield, and a judgment unit to judge the state of the
windshield from the state of the image of the comparable object
taken in by the camera.
[0003] [Patent Literature 1] JP-A-10-111249
DISCLOSURE OF THE INVENTION
Technical Problem
[0004] In Patent Literature 1, the visibility state is detected, an
internal target detection value (distance dispersion, etc.) is made
a threshold, and the wiper control is performed. Since various
factors influence the detection value, there are problems that if
the threshold is not expected to be inappropriate, the detection
value exceeds the threshold and erroneous operation increases, and
if the accuracy is attempted to be raised, the time required for
the control becomes long.
[0005] An object of the invention is to provide a wiper control
apparatus which detects a visibility state of a window of a moving
body and controls a wiper to a target visibility state with less
erroneous operation and in a short time.
Solution to Problem
[0006] In order to solve the problem, a wiper control apparatus of
the invention includes a wiper position detection unit to detect a
position of a wiper on a window of a vehicle, a recognition rate
calculation unit to calculate a recognition rate of an image taken
by an imaging device when the position of the wiper detected by the
wiper position detection unit is a previously determined position,
a target recognition rate setting unit to set a target recognition
rate from the calculated recognition rate, a comparison unit to
compare the recognition rate with the target recognition rate and
to output a comparison result, and a wiper operation speed
determination unit to determine an operation speed of the wiper
based on the comparison result.
Advantageous Effects of Invention
[0007] According to the invention, a wiper control apparatus can be
provided which detects a visibility state of a window of a moving
body and controls a wiper to a target visibility state with less
erroneous operation and in a short time.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a view showing a mount position of a camera seen
from a side direction of a vehicle according to the invention.
[0009] FIG. 2 is a view showing the mount position of the camera
seen from a front direction of the vehicle according to the
invention.
[0010] FIG. 3 is a view showing an example of a control method of a
wiper control apparatus of the invention.
[0011] FIG. 4 is a view showing a relation between a wiper
operation of the wiper control apparatus of the invention and a
recognition rate.
[0012] FIG. 5 is a view showing an example of the definition of the
recognition rate of the wiper control apparatus of the
invention.
[0013] FIG. 6 is a view showing another example of the definition
of the recognition rate of the wiper control apparatus of the
invention.
[0014] FIG. 7 is a view showing object pixels of an imaging device
for recognition rate calculation of the wiper control apparatus of
the invention.
[0015] FIG. 8 is a view for explaining a wiper position detection
unit of the wiper control apparatus of the invention.
[0016] FIG. 9 is a view showing the definition of a recognition
rate when wiper control is performed by two cameras in the wiper
control apparatus of the invention.
REFERENCE SIGNS LIST
[0017] 1 camera
[0018] 2 window
[0019] 3 wiper
[0020] 4 wiper position detection unit
[0021] 5 recognition rate calculation unit
[0022] 6 storage device
[0023] 7 target recognition rate setting unit
[0024] 8 comparison unit
[0025] 9 wiper operation speed determination unit
[0026] 18 taken image
[0027] 19 noted pixel
[0028] 20 adjacent pixel
DESCRIPTION OF EMBODIMENTS
[0029] Hereinafter, examples will be described with reference to
the drawings.
EXAMPLE 1
[0030] In this example, an example of a wiper control apparatus of
the invention will be described with reference to FIG. 1 to FIG.
8.
[0031] FIG. 1 shows amount position of a camera 1 as an imaging
device seen from a side direction of a vehicle, and FIG. 2 shows it
seen from a front direction. FIG. 3 shows a wiper control method of
a wiper control apparatus, FIG. 4 shows a relation between a wiper
operation and a recognition rate, and FIG. 5 and FIG. 6 show
examples of definition of the recognition rate. FIG. 7 shows object
pixels of an imaging device for recognition rate calculation, and
FIG. 8 shows an example of a wiper position detection unit.
[0032] The camera 1 as the imaging device to recognize the outside
world through a window 2 as a window of a vehicle is placed on the
vehicle. The window 2 is provided with a wiper 3. The camera 1
monitors a range in which the wiper 3 wipes. When the wiper 3
starts to operate, A shown in FIG. 2 performs a simple
oscillation.
[0033] Next, an example of a wiper control method of the wiper
control apparatus of the invention will be described with reference
to FIG. 3.
[0034] A wiper position detection unit 4 is provided in the wiper
3, and detects the position of the wiper 3 on the window 2. As a
result of the detection by the wiper position detection unit 4,
when the wiper 3 is located at a previously determined specified
position, a recognition rate calculation unit 5 calculates a
recognition rate of an image taken by the camera 1, and the
calculated recognition rate is stored in a storage device 6. When
stored in the storage device 6, the calculated recognition rate may
be correlated with the position of the wiper 3 and may be
stored.
[0035] A target recognition rate setting unit 7 sets a target
recognition rate of the taken image, and a comparison unit 8
compares the recognition rate calculated by the recognition rate
calculation unit 5 with the target recognition rate set by the
target recognition rate setting unit 7. A wiper operation speed
determination unit 9 determines the operation speed of the wiper 3
based on the comparison result. For example, as a result of the
comparison, if a difference value between the calculated
recognition rate and the target recognition rate is larger than a
previously determined value (if the visibility state of the window
2 is bad), the wiper operation speed determination unit 9 outputs a
control signal to increase the operation speed of the wiper 3. If
the difference value between the calculated recognition rate and
the target recognition rate is smaller than the previously
determined value (if the visibility state of the window is
excellent), the wiper operation speed determination unit 9 outputs
a control signal to decrease or stop the wiper operation. Besides,
plural kinds of control signals for wiper operation speed are
stored in advance, and an optimum control signal may be outputted
by selecting one of the plural control signals based on the
comparison result of the comparison unit 8. Incidentally, from FIG.
4, the target recognition rate setting unit 7 previously sets the
recognition rate of the image, which is taken by the camera 1 after
the wiper 3 wipes, as the target recognition rate.
<Relation between Wiper Operation and Recognition Rate>
[0036] The details of a relation between the wiper operation and
the recognition rate will be described with reference to FIG.
4.
[0037] A lower limit position of wiper position in the vertical
direction (on the side close to the ground) is made A, an upper
limit position is made C, and a front position of the camera 1 is
made B. The wiper 3 performs a repeating operation of
A.fwdarw.B.fwdarw.C.fwdarw.B.fwdarw.A.fwdarw. in a time axis. At
this time, the recognition rate of the camera 1 becomes highest
just after B, and thereafter, as long as the position is not
returned to the position B again, the recognition rate deteriorates
with the time axis. At the time of rain, since raindrops are
attached to the surface of the window 2 with the time, the
recognition rate deteriorates. However, just after B, since the
wiper 3 wipes in the monitor range of the camera 1, the recognition
rate becomes high.
[0038] As described before, the recognition rate just after B as
the target recognition rate is estimated from the recognition rate
at the specified position of the wiper 3, and the target value
estimated from the factor of fluctuation of the recognition rate by
the wiper 3 is set. By this, the influence on the recognition rate
by the change of external environment except for what can be
improved by the wiper 3 can be cancelled. Thus, an erroneous
operation can be decreased and it is said to be excellent. The
difference between the target value and the actual recognition rate
is made proportional to the wiper operation speed, so that a
remarkable effect is obtained that the wiper control can be settled
to the target in a short time.
<Example of Recognition Rate>
[0039] FIG. 5 shows an example of the recognition rate. The
recognition rate is set from a change amount in light amount
between a noted pixel 19 in a taken image 18 taken by the camera 1
and an adjacent pixel 20 adjacent to the noted pixel 19. When a
raindrop is attached to the window 2, a focus value of the camera 1
optimized when there is no raindrop is shifted by the lens effect
of the raindrop. That is, when an object is monitored, the change
amount in light amount between the noted pixel 19 and the adjacent
pixel 20 becomes small. Accordingly, when the recognition rate is
defined as stated above, as the amount of attached raindrops
increases, the change amount in light amount decreases over the
whole area of the taken image 18. Thus, since the deterioration of
the recognition rate with the time shown in FIG. 4 can be
reproduced, it is said to be one of excellent indexes.
[0040] FIG. 6 shows another example of the recognition rate. The
recognition rate is set from a difference amount in light amount
between an image of a just previous time frame and an image of a
current time frame in the taken image 18 taken by the camera 1.
When the pixel light amount is represented by p, a row direction is
represented by i, a column direction is represented by j, and a
time axis is represented by t, the respective pixel light amounts
at time t-1 and t are pij_t-1(10) and pij_t(11).
[0041] In this example, the recognition rate is the total sum of
the pixel light amounts pij_t.about.pij_t-1 over the taken image
area.
[0042] When a raindrop is attached to the window 2, the focus value
of the camera 1 optimized when there is no raindrop is shifted by
the lens effect of the raindrop. That is, a change in light amount
occurs before and after the attachment of the raindrop.
Accordingly, when the recognition rate is defined as stated above,
as the amount of attached raindrops increases, the change amount in
light amount increases over the whole taken image area. Thus, the
deterioration of the recognition rate with the time shown in FIG. 4
can be reproduced, and it is said to be one of excellent
indexes.
<About Recognition Object>
[0043] FIG. 7 shows an example of a pixel range of a taken image 18
as an object when the recognition rate is calculated.
[0044] When the camera 1 is mounted in the vehicle, the camera is
arranged so that a vehicle body portion 12 falls within the viewing
angle of the camera 1, and the calculation of the recognition rate
is performed on the vehicle body portion 12 falling within the
viewing angle. By this, since the change of the recognition rate
due to the change of the object can be reduced, an erroneous
operation of the wiper 3 can be reduced.
<Wiper Position Detection Unit>
[0045] FIG. 8 shows an example of the wiper position detection unit
4.
[0046] The wiper 3 is recognized twice by image recognition in the
movement process of the wiper 3 of the upper limit in the vertical
direction.fwdarw.the lower limit and the lower limit.fwdarw.the
upper limit, respectively, and the recognition is repeated
thereafter. This is because the operation range of the wiper 3 is
mechanically previously determined, and the upper limit position of
the wiper 3 in the vertical direction and the lower limit position
are previously determined. Accordingly, two intermediate times are
respectively made the upper and lower limit positions of the wiper
position, and a position of the wiper 3 at an arbitrary time is
estimated by temporal linear interpolation, so that wiper position
detection can be performed. By this, even if there is no sensor for
detecting the wiper position, the wiper position can be estimated,
and this is excellent. Further, even if a vehicle is changed, the
recognition algorism is not changed. Thus, as compared with the
case where information of a wiper position sensor is used, since
less vehicle adaptation is required, this is excellent.
[0047] Incidentally, with respect to the operation speed of the
wiper, the operation speed is made constant in the range of one
simple oscillation. Thus, the change of the wiper speed is
performed only at the base point of the specified position where
the recognition rate is measured.
EXAMPLE 2
[0048] In this example, a description is made on an example of a
wiper control apparatus in which the camera 1 as the imaging device
of the example 1 is not a single body, and wiper control is
performed by plural cameras. For example, a wiper control apparatus
performs the wiper control by a stereo camera using two
cameras.
[0049] FIG. 9 shows an example of a recognition rate when an image
is taken by using two cameras. In a state where one camera (left
camera) and the other camera (right camera) are arranged side by
side in the right and left horizontal direction, when a pixel of a
taken image 18 of the left mount camera in the traveling direction
is denoted by Left, and a pixel on the right side is denoted by
Right, each pixel light amount is Left_pij_t(12),
Right_pij_t(13).
[0050] In this example, the recognition rate is the total sum of
Left_pij_t.about.Right_pij_t over the taken image area. When a
raindrop is attached to the window 2, the focus value of the camera
1 optimized when there is no raindrop is shifted by the lens effect
of the raindrop. That is, a change in light amount occurs before
and after the attachment of the raindrop. Since raindrops on the
window 2 seen from the right and left cameras 1 are different, the
change amount in light amount over the whole taken image area
becomes large. Thus, since the deterioration of the recognition
rate with the time shown in FIG. 4 can be reproduced, it is said to
be one of excellent indexes.
[0051] Besides, inner parameters of the right and left cameras are
derived from the imaging result, and the change amount thereof is
defined as the recognition rate. When a raindrop is attached to the
window 2, the inner parameter is changed by the lens effect of the
raindrop from that obtained when there is no raindrop. That is, the
change of the value of the inner parameter occurs before and after
the attachment of the raindrop. Accordingly, when the recognition
rate is set from the change amount of the inner parameters, the
deterioration of the recognition rate with the time shown in FIG. 4
can be reproduced similarly, and it is said to be one of excellent
indexes.
[0052] Various merits of the single camera are obtained also in the
case of the plural cameras.
* * * * *